Dynamical Friction of Double Perturbers in a Gaseous Medium

Understand

In many astrophysical situations, as in the coalescence of supermassive black hole pairs at gas rich galactic nuclei, the dynamical friction experienced by an object is a combination of its own wake as well as the wakes of its companions.

• Using a semi-analytic approach, we investigate the composite wake due to, and the resulting drag forces on, double perturbers that are placed at the opposite sides of the orbital center and move on a circular orbit in a uniform gaseous medium.
• The circular orbit makes the wake of each perturber asymmetric, creating an overdense tail at the trailing side.
• The tail not only drags the perturber backward but it also exerts a positive torque on the companion.